Final answer:
Kevlar is a material stronger than steel but it is susceptible to degradation from ultraviolet light in sunlight.
Step-by-step explanation:
The answer to the question 'What's stronger than steel but can't handle the sun?' is c) Kevlar. Kevlar is a synthetic fiber known for its high tensile strength and thermal stability, making it stronger than steel on an equal weight basis. However, it has a weakness to ultraviolet (UV) light found in sunlight, which can degrade the material over time. Unlike Kevlar, materials like aluminum, titanium, and carbon fiber do not have the same vulnerability to UV degradation.